/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.io;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.Socket;

import org.apache.http.io.EofSensor;
import org.apache.http.io.SessionInputBuffer;
import org.apache.http.params.HttpParams;

/**
 * {@link SessionInputBuffer} implementation bound to a {@link Socket}.
 * <p>
 * The following parameters can be used to customize the behavior of this class:
 * <ul>
 * <li>{@link org.apache.http.params.CoreProtocolPNames#HTTP_ELEMENT_CHARSET}</li>
 * <li>{@link org.apache.http.params.CoreConnectionPNames#MAX_LINE_LENGTH}</li>
 * <li>{@link org.apache.http.params.CoreConnectionPNames#MIN_CHUNK_LIMIT}</li>
 * </ul>
 * 
 * @since 4.0
 */
public class SocketInputBuffer extends AbstractSessionInputBuffer implements
		EofSensor {

	@SuppressWarnings("rawtypes")
	static private final Class SOCKET_TIMEOUT_CLASS = SocketTimeoutExceptionClass();

	/**
	 * Returns <code>SocketTimeoutExceptionClass<code> or <code>null</code> if
	 * the class does not exist.
	 * 
	 * @return <code>SocketTimeoutExceptionClass<code>, or <code>null</code> if
	 *         unavailable.
	 */
	@SuppressWarnings("rawtypes")
	static private Class SocketTimeoutExceptionClass() {
		try {
			return Class.forName("java.net.SocketTimeoutException");
		} catch (ClassNotFoundException e) {
			return null;
		}
	}

	private static boolean isSocketTimeoutException(
			final InterruptedIOException e) {
		if (SOCKET_TIMEOUT_CLASS != null) {
			return SOCKET_TIMEOUT_CLASS.isInstance(e);
		} else {
			return true;
		}
	}

	private final Socket socket;

	private boolean eof;

	/**
	 * Creates an instance of this class.
	 * 
	 * @param socket
	 *            the socket to read data from.
	 * @param buffersize
	 *            the size of the internal buffer. If this number is less than
	 *            <code>0</code> it is set to the value of
	 *            {@link Socket#getReceiveBufferSize()}. If resultant number is
	 *            less than <code>1024</code> it is set to <code>1024</code>.
	 * @param params
	 *            HTTP parameters.
	 */
	public SocketInputBuffer(final Socket socket, int buffersize,
			final HttpParams params) throws IOException {
		super();
		if (socket == null) {
			throw new IllegalArgumentException("Socket may not be null");
		}
		this.socket = socket;
		this.eof = false;
		if (buffersize < 0) {
			buffersize = socket.getReceiveBufferSize();
		}
		if (buffersize < 1024) {
			buffersize = 1024;
		}
		init(socket.getInputStream(), buffersize, params);
	}

	@Override
	protected int fillBuffer() throws IOException {
		int i = super.fillBuffer();
		this.eof = i == -1;
		return i;
	}

	@Override
	public boolean isDataAvailable(int timeout) throws IOException {
		boolean result = hasBufferedData();
		if (!result) {
			int oldtimeout = this.socket.getSoTimeout();
			try {
				this.socket.setSoTimeout(timeout);
				fillBuffer();
				result = hasBufferedData();
			} catch (InterruptedIOException e) {
				if (!isSocketTimeoutException(e)) {
					throw e;
				}
			} finally {
				socket.setSoTimeout(oldtimeout);
			}
		}
		return result;
	}

	@Override
	public boolean isEof() {
		return this.eof;
	}

}
